php - 在 SQL 语句中使用 PHP 变量

Question

我正在使用 WordPress，并且有一个 SQL 语句(如下所示)来收集特定类别的标签。唯一的问题是表名可能会改变(即它们并不总是 wp_*)。函数 $pfx = $wpdb->base_prefix; 返回 wordpress 数据库前缀。

如何在下面的 SQL 语句中使用 $pfx (而不是 wp_ )。

global $wpdb;
$tags = $wpdb->get_results
("
SELECT DISTINCT terms2.term_id as tag_id, terms2.name as tag_name, null as tag_link, t2.count as post_total
    FROM
        wp_posts as p1
        LEFT JOIN wp_term_relationships as r1 ON p1.ID = r1.object_ID
        LEFT JOIN wp_term_taxonomy as t1 ON r1.term_taxonomy_id = t1.term_taxonomy_id
        LEFT JOIN wp_terms as terms1 ON t1.term_id = terms1.term_id,

        wp_posts as p2
        LEFT JOIN wp_term_relationships as r2 ON p2.ID = r2.object_ID
        LEFT JOIN wp_term_taxonomy as t2 ON r2.term_taxonomy_id = t2.term_taxonomy_id
        LEFT JOIN wp_terms as terms2 ON t2.term_id = terms2.term_id

    WHERE
        t1.taxonomy = 'category' AND p1.post_status = 'publish' AND terms1.term_id IN (".$args['categories'].") AND
        t2.taxonomy = 'post_tag' AND p2.post_status = 'publish'
        AND p1.ID = p2.ID
    ORDER BY post_total DESC
");

谢谢。

Answer 1

例如更改

LEFT JOIN wp_term_relationships 

进入

LEFT JOIN ".$pfx."term_relationships